wheelshaft
Scientific Revelation：
wheelshaft，As the name suggests, it is caused by“wheel”and“shaft”The system composed。The system can rotate around a common axis，It is equivalent to taking the axis as the fulcrum，A lever system with a radius of a rod。So，The axle can change the torque，So as to change the magnitude of the torque。A common windlass in daily life、Winch、Stone mill、The steering wheel of a car、Wrench、Hand-cranked winch、自来water龙头的扭柄等都是wheelshaft类机械。
Scientific principles：
wheelshaft的实质是可以连续旋转杠杆．When using wheel axles，一般情况下作用在wheel上的力andshaft上的力的作用线都与wheelandshaft，"Tangent"，Therefore，它们的力臂就是对应的wheel半径andshaft半径。由于wheel半径总大于shaft半径，Therefore当动力作用于wheel时，The axle is a lever that saves effort and distance（The first picture below），Actual examples：有自行车脚踏与wheel盘（Large gear）是省力wheelshaft．When power acts on the shaft，wheelshaft为费力省距离杠杆（As shown in the second picture below），Actual examples include：自行车后wheel与wheel上的飞盘（小齿wheel）、吊扇的扇叶andshaft，都是费力wheelshaft的应用． F1R=F2r The axle is a simple mechanical device that saves effort。（wheel半径大，shaft半径小，So省力）
Scientific production：
1，Recognize and prepare the materials needed for the experiment。
2，Install in sequence according to the steps in the manual。
3，After installation is completed, proceed with debugging。
Scientific expansion：
Archimedes of ancient Greece was the earliest inventor of the water pump in history．Archimedes was born in the BC era287The ancient city of Syracuse in Greece in that year．At that time, the economy of Syracuse was unprecedentedly prosperous，The trend of scientific research is very strong，Many people in the city are interested in philosophy、He has conducted considerable research in geometry and other fields．They like debating.，Take this as an opportunity to learn，Archimedes grew up in such an atmosphere，Developed a fondness for thinking、The good habit of liking to study。A Sunday，阿基米德and同学们一起乘木船，Drive slowly on the Nile River，The charming scenery on both banks left him dazzled．Suddenly，他看到一群人在用木桶拎water，Then he asked：“他们干嘛要拎water?”“The riverbed terrain is low.，The terrain of the farmland is high.，农民只好拎water浇地了。”A local classmate told him。“Like this拎water的效率太低了，How many buckets are needed to water a plot of land。”Archimedes felt compassion for the farmers in his heart。 After returning，阿基米德的眼前总是闪现出农民拎water时吃力的样子．“Could water be made to flow higher?”Archimedes began to think about this question．Gradually，An idea emerged in Archimedes' mind：“Make a big spiral，Put it in a cylinder。Like this，After the spiral starts to rotate，water不就可以沿着螺旋沟带到高处去了吗?”Archimedes immediately followed this idea，A sketch was drawn．He took the sketch to the carpenter，请求师傅帮他做一个用于泵water的工具．”Guided by Archimedes，The carpenter made a strange thing．Archimedes moved this thing to the river，And put one end of it into the river，Then gently shake the handle．“Gurgle gurgle”，只见河water在摇动手柄的同时，It kept gushing out from the top of the strange thing。water，Sure enough, it flowed upwards。
